In printing systems, line width is a critical customer image quality attribute as it relates to text quality. The ability to set and maintain line width is desirable. In some control systems, line width variation in the presence of system noises is controlled by setting exposure and cleaning field in response to ETAC sensor readings of a halftone patch. The correlation of line width to halftone patch readings is reasonable but not completely accurate. In system testing, line width variation has a significant residual as toner age varies, for example, from 10 min to 120 min.
To be described in more detail hereinafter, aspects of the present disclosure and embodiments thereof include methods and systems for adjusting aspects of images. For example, methods and systems may be employed to control line width in image objects, such as, for example, text and line art. Embodiments will be described with reference to line width adjustments and laser power adjustments. However, embodiments may be applied to the adjustment of other aspects of image objects.
It should be noted that the term line, or lines, is meant to refer herein to any relatively thin image object, including, but not limited to, curves and circles.
Many images include thin lines. For example, the characters of text are considered to be made up of thin lines and curves. Additionally, many business forms include lines and grids for separating portions of a document. Many drawings are made up of discreet thin lines. It is desirable to be able to adjust images in order to enhance or improve their appearance. For instance, it may be desirable to adjust the width or thickness of lines in an image.
For example, one way to adjust the darkness or lightness or enhance the contrast of a document being printed or photocopied is to adjust the width or thickness of lines. Additionally, it may be desirable to adjust the width of lines in an image in order to compensate for a drift or imperfection in an image rendering system. For instance, ink or toner may spread or be absorbed by a print media more or less readily than anticipated. If an ink spreads more readily than an ideal or anticipated amount, then, for example, a white line or feature printed on a black, gray or colored background, might appear thinner than desired or may be completely filled in by spreading colorant from neighboring portions of an image. If ink or toner or other colorant spreads less readily than anticipated, then a black, gray or colored line may appear thinner than desired.
Line widths can also vary in association with the aging of toner in the housing. Line width variations can have a significant residual as toner age varies from, for example, 10 minutes to 120 minutes. The present disclosure proposes correcting for line width variation versus toner age using a model of line width versus exposure or laser power to determine an exposure correction value for a nominal exposure setting.
U.S. Patent Application Publication US20060285764 to Beilei, et al. published Dec. 21, 2006, entitled Model-based line width control, discusses methods for controlling the width of lines in an image in order to compensate for drift or imperfections in an image rendering system. For instance, ink or toner may spread or be absorbed by a print media more or less readily than anticipated. The disclosure of the above cited patent application is incorporated herein by reference.
There has been a desire for line width control techniques with reduced system storage requirements. Additionally, there has been a desire for line width control techniques that do not require, or require fewer, data lookups and comparisons. Further, there is a desire for line width control methods that can be efficiently adapted to related applications, thereby greatly reducing the design effort.